Apparatus for regulating the flow of thixotropic colloids and the like



Feb. 26, 1952 W. E. MCFADDEN APPARATUS FOR REGULTING THE FLOW OF' THIXOTROPIC COLLOIDS AND THE LIKE 2 SHEETS--SHEET l Filed Oct. 18, 1945 ml HM l W. E. MCFADDEN 2,587,88 APPARATUS FOR REGULATING THE FLOW OF THIXOTROPIC COLLOIDS AND THE LIKE Feb. 26, 1952 2 SHEETS-SHEET 2 Filed Oct. 18, 1945 Edie):

Patented Feb. 26, 1952 UNITED STATES` oFFics APPARATUS FoRf' REGUBATING THE: FLOW. 'onl THiXoTRjoPIc COLLQ;DVS.,I`AND, THE,

Canada, assighnr 'to `Hudso Bay-(Mining and.V

Smelting Co2, Limited, W1nn1peg;Ma nitolia Gwada This'. invention relatesto. a. method and ,ap-r

paratus for regulating'the flow of certain types of iluid Vsuch as thixotropiccolloids.which mustl and heavy slurries and pastes which: stick to and clog. valveparts and 'in somecases jell or stiffen when. allowed to remainV motionless, are very, difficult to handle. They are commonly conveyed in tubing (whichv term is Aused herein .tc include a series fof.' connected pipesl'and a greatneed has been. felt forapparatus 'suitable for. regulating the flow of such fluids Vinthe tubing. Thus the apparatus accordingto the present invention, which .regulates thev flowvv ofY such fluids while maintaining the same in. a state of agitation, has a Wide application in', for example, the fields of ore dressing, refractory slips, Portland cement, sea-water treatment for the recovery of values, and food processing.

Theilow. regulating apparatus according to the present invention has been designed for and has particular applicationto` the. regulation of the flow of those materials known as thixotropic colloids. It is typicalof't-hese Athixotropic co1- loids that, on standing for a short time;l theyA act like a solid-,exhibiting Vlittle-giorno. tendency to flow, and if cut with a knife maintain theirshape.v

On being vigorously stirred, however, they become quite fluid,r and behave like a -viscous liquidrbut on cessation .of agitation they, soon stiien,and act like asolid. An'example of 'such a material is the residue left after the treament of Zincores by standard hydro'metallurgical treatment. This material is essentially zinc'rferriterwith more or less ferrie hydroxide, zinc sulphate, zinc .sul-,-

phide and small quantities of other constituents formed. into a pulpv with water, 'the lattencomprising to 40% of the Weight.

In many methods of treating such materials it is necessary that they be fed to various operations in a uniform manner. One method of doing this is to place the material in a tank, agitate it by mechanical stirrers until it is fluid and then let it ilow to the next stage of the process through pipes or tubing provided with one or more valves whose openings may be regulated. Ordinary valves are quite unsatisfactory for this process because when they are partly shut off, the material is not sufficiently agitated in the valves or in the pipe leading to the valves so that the material reverts to the solid form and clogs the valve and the pipes.

The object of the present invention is to provide a method and apparatus for controlling the flow in tubingconveying @fluids` of.V the: kind. def

scribed` While maintaining the san-1ey in a .state of agitation.

More specifically-an yobject of the invention isto .providea method for conveying such fluids in which the same are passed throughtubing including a flexible tube,vand thecross ksection of the flexible tube is .altered xcyclically by cyclically. increasing and vdecreasing external pressurev on.- the. tube.

A further specific object of the invention Aisfto provide apparatus vfor connectionin tubingifor conveying fluidsof therkind describecl, comprising a'iflexible tubeand means-for cyclicallydecreasing. the cross section of the flexible. tube and allowing it to expand.

Afurther specific object ofthe invention is Ato provide in combination with-.such apparatusadjustable means. for`varying the proportionsof the cycle of increase and release of pressure to adjust .the vrate of flow through the tubing.

Other objectsand features-of the invention will f appear from the rfollowing description with reference .tothe drawings .in lwhich-.-

Figure 1 is a section .in 4elevation of the.ap. paratus according to the invention, and.

Figure A2 is an end view-of the:app aratustaken onasection through the relief valve, and showing themechanism for cyclically actuating .the relief The apparatus:consists-basically of the flexible.

tubefl; andtubular housingII defining between them the, air chamber I2, and-of the inlet tube I3.and relief ,valve Ill.. The flexible-tube which is threadecl. .,ontovr the housing I.I

ment to pipes leading respectively to an agitator tank and to the next stage of the treatment process, cooperate with the flanges I6 to firmly engage the flanges I5 and effect a tight seal between the flanges I5 and I6, thereby preventing the escape of air from the chamber l2. The flanges I6 and I'I are tightened down onto the flanges I5 by means of the bolts I9 and nuts 20, the former being passed through suitable aligned holes formed in the ilanges I5, I6 and I'I. When a fluid under pressure, for example air, is admitted through the inlet pipe I3, the rubber tube I0 is constricted as indicated at 2I, the extent of constriction depending on the pressure applied and the duration of application.

The relief valve I4 consists of a seat 22 in the a tight seal with the seat 22.

form of a tube which may be welded or otherwise secured to the housing Il in line with a hole formed therein, a valve member 23, and a washer 24 carried by the valve 23 and arranged to eiect Because the diameter of the seat 22 is relatively large the pressure in the chamber l2 may be immediately dropped by lifting the member 23 and its washer 24, thereby allowing the tube l to be expanded by the fluid passing through it. By opening and closing the valve I4 in a suitable cyclic manner, the rate of passage of fluid through the tube I0 may be accurately controlled, and moreover the fluid in the tube I0 and in the pipes preceding and following it may be kept in a state of agitation so that, in the case of a thixotropic colloid, it remains fluid.

A convenient arrangement for cyclically and automatically actuating the relief valve I4 is shown in Fig. 2. The member 23 carrying the gasket 24 is connected to an arm 25 which is of sucient weight to normally hold the relief valve closed. This arm 25 is hinged at one end to pivot between two angle members 21 on a pin 26 supported at its ends by the angle members 21 and secured by a nut 28. The angle members 21 are conveniently connected by bolts 29 to the base 30 which supports the housing Il. The angle members 21 are further supported by a brace 3l extending between each angle member 21 and the housing Il.

When the lfree end of the arm 25 is lifted to cause it to pivot on the pin 26 the member 23 and gasket 24 are lifted from the seat 22. To the free end of the arm 25 there is connected an extension 32 which extends into the path travelled, in the direction indicated by the arrow, by a cam member 33 carried by a wheel 34 rotated through speed reducer 35 and a suitableV coupling 36 by a motor 31, the speed reducer 35 and motor 31 being mounted on a base 38. As the wheel 34 revolves it brings the arm 33 into contact with the underside of the extension 32 thereby pivoting the arm 25 and lifting the member 23 and its gasket 24 from the seating 22.

It will be observed that the length of time during which the relief valve is opened is dependent on the length of time during which the extension 32 is engaged by the member 33 and that 'this may be regulated by shortening and lengthening the distance which the member 33 projects from the Wheel 34. Accordingly the member 33 is provided with suitable slots 39 through -which pass bolts 40 for securing the member 33 to the wheel 34. lThus when it is desired to increase the rate of flow through the tube I0, and for this purpose to decrease the duration of the increase of pressure on the tube I, the distance which the arm 33 extends from the wheel 34 is increased. The result is to produce a cyclic contraction and 4 expansion of the tube which prevents the uid therein from coming to rest.

What I claim is:

1. Apparatus for controlling the ow in tubing conveying uids requiring to be maintained in a State of agitation, comprising a exible tube adapted for connection in said tubing, a housing enclosing at least a portion of the flexible tube and defining therewith a sealed chamber surrounding the same, means for admitting a separate fluid under press-ure to such chamber, and means for causing the pressure exerted by such separate uid on the flexible tube to increase and decrease cyclically to decrease the cross-section of the flexible tube, and therefore allow it to increase cyclically.

2. Apparatus as defined in claim 1 in which said means for causing the pressure exerted by the uid to increase and decrease comprises a relief valve operable to relieve pressure in said chamber and means for intermittently opening and closing the same.

3. Apparatus as defined in claim 2 in which said means for intermittently opening and closing the relief valve comprises a hinged arm normally bearing on the relief valve to hold said valve closed, a cam member, and means for causing said cam member cyclically to engage the hinged arm and move said arm to open the relief valve.

4. A device as defined in claim 2 in which said means for intermittently opening and closing the relief valve comprises a hinged arm normally bearing on the relief valve to hold said valve closed, a cam Wheel, means for driving the cam Wheel and a cam lever projecting from the wheel to travel a circular path into which the free end of the hinged arm projects, whereby said cam lever cyclically engages the free end of said hinged arm to move the same to open the relief valve.

WILLIAM EVANS MCFADDEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 493,733 McGahan Mar. 21, 1893 821,184 Oakes May 22, 1906 1,427,455 Gates Aug. 29, 1922 2,348,402 Miller May 9, 1944 2,380,969 King Aug. 7, 1945 FOREIGN PATENTS Number Country Date 540,685 Great Britain of 1941 371,681 Italy of 1939 

